For many cosmetic formulations it is desirable to provide volumizing effect to hair, eyelashes and/or eyebrows. Especially mascaras are used to achieve expansion of eyelashes or eyebrows.
US 2006/0147399A1 discloses post-application expanding compositions for application to hair, eyelashes or eyebrows that use in situ generated CO2 to foam one or more surfactant components of the composition. A film-forming component of the composition is used to entrap at least a portion of the foam lattice and, when set, fix the composition in an expanded state. This two-part system which is described on pages 18 to 21 of the above application uses an anhydrous carbonate or bicarbonate and an anhydrous acid, preferably citric acid, in an anhydrous mascara composition which is mixed on the eyelashes with an aqueous top composition containing the surfactant and preferably the film forming agent. The CO2 which is produced acts to foam the surfactant and the solvent for the surfactant. When the film-forming agent, which is preferably present in the aqueous solution sets, it entraps the produced foam or a portion thereof. To suspend the anhydrous acid and base without co-reacting anhydrous polyethylene glycol, sorbitol and glycerin are the suggested solvents in the base coat of the above application. However, the resulting films are instable and the volumetric effect is short lived.
US 2006/0216257 discloses an alternative post-application expanding composition to produce a volumetric effect. That composition consists of an oily and an aqueous part wherein the oily part comprises at least one polyelectrolyte. After combination of the two parts the polyelectrolyte acts as a “water pump”. The resulting film becomes hydrated and swells. However, these films dry out easily and instability issues arise. Further, the usually generated volumetric effect generated by applying a water topcoat over a water swellable film is negligible, because such films need to be mixed well. To improve the volumetric effect surfactants are added to the composition. However, a foam structure which is achieved using surfactants is very instable so that the resulting effects are short lived.
It would be desirable to have a cosmetic formulation with a long lasting volumizing effect to hair, eyebrows and eyelashes, especially a mascara, which overcome the above mentioned problems of the compositions of the prior art. The desired cosmetic formulation should provide a clear, smooth, flexible and durable film on the hair fibers which satisfies the aesthetic requirements of the consumers.
The composition should also be easy to produce in a cost-efficient manner. Due to safety concerns it also is desirable to avoid the use of aggressive conditions near the eyes, e.g. the use of citric acid.